1. Technical Field
The present disclosure relates to a method of manufacturing a nitride semiconductor element.
2. Background Art
Semiconductor light emitting elements such as light emitting diodes (hereinafter may be referred to as “LEDs”), laser diodes (hereinafter may be referred to as “LDs”) have a small size and good power efficiency, and emit light of bright colors, and have been used for various light sources. Semiconductor light emitting elements are attracting attention as next-generation lighting because of their low energy consumption and long life, and further improvement in light output power and luminous efficiency have been required.
Of those semiconductor light emitting elements, a manufacturing of particularly nitride semiconductor elements includes dividing a wafer which is a nitride semiconductor stacked on a substrate into individual nitride semiconductor elements. In recent years, a laser dicing technology has been employed in a dividing process, in which a laser beam is focused on a surface or an inner portion of an objective material (for example, a wafer) to form an altered portion which is to serve as a division starting point, and an external force is applied to generate a dividing groove or a crack to split the wafer.
See JP 2008-98465A.
However, not only in the case where the laser beam is irradiated from the nitride semiconductor layer side but also in the case where the laser beam is irradiated from the substrate side, damage to the nitride semiconductor layer caused by the laser beam which passed the wafer has been of concern. Such damage includes, regardless of a scar in the appearance of the nitride semiconductor layer, a state in which the nitride semiconductor layer does not normally function. A damaged nitride semiconductor layer may lead to leakage and/or a low-voltage breakdown. Such influence of a laser beam on a nitride semiconductor layer can be reduced by reducing the laser output or reducing the number of irradiation of the laser beam, but on the other hand, an increase in the tact time and/or a decrease in yield due to occurrence of an undivided portion at the time of dividing the wafer or due to ununiform shapes after dividing the wafer may occur. Further, the greater the thickness of the wafer, the greater the laser beam output needed to divide the wafer, which also increases the number of irradiation of the laser beam. For the reasons described above, the possibility of damaging the semiconductor layer increases.
The present disclosure is provided to solve the problems described above, and an aim thereof is to reduce damage of the nitride semiconductor layer caused by a laser beam.